Epsom Common has a variety of habitats: woodland; grassland; scrub and remnants of heathland. Consequently, there are more than 400 species of trees and plants, which provide habitats for a range of mammal, bird and insect species. Due to the variety of insect life, around 30 species of Britian's 60 native butterflies have been recorded on the Common, there are over 100 species of birds such as blue tits, great tits, wrens and woodpeckers and herons are commonly seen at the Great Pond.

Epsom Common is important for its lowland heath and its status as a Site of Special Scientific Interest is for a range of rare flowering plants, such as the Common Spotted and Southern Marsh Orchids. There are also pollarded oak trees, which are several hundred years old and are home to a number of rare insects, such as the Purple Emperor and the White Admiral butterflies.The Common has several ponds, Stew Pond, Great Pond, Stamford Green Pond, Baron's Pond and Blake's Pond.

There are also many small ponds dotted around the Common, which often dry up in summer. This is just enough time for amphibians like frogs and newts to spawn and breed before the water dries up and they have to leave for the safety of damp places. The Great Pond is protected from fishing and is kept as a wildlife reserve for pond-life, amphibians and resident wildfowl such as coots, moorhen, mallard, tufted duck, great crested grebes, swans and herons. The water is also visited by less common wildfowl in the winter. Stew Pond is the only pond in which fishing is allowed and is used by the CALPAC - Central Association London Provincial Angling Clubs (Angling for ALL).There is also a population of roe deer on the Common.